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Topic Review (Newest First)

11-02-2007 11:42 PM

HoffaLives

[QUOTE=camaraderie;216282]Hoffa...sorry but that is not right. Wet cell batteries can only take about MAXIMUM of 20% of capacity during bulk charging which means that a 60amp altenator is fine for a 300ah bank.
Even with charging system loss...fully charging is simply a matter of time. Incomplete charging can happen with ANY size charger and is definitely a problem if you don't monitor what is happening in your charging routine.

I'll have to double-check on that 20% figure of yours, but the problem is losses due to poor design (which is standard), lots of crummy connections (ditto), and recharge time. It would be easy to draw down the batteries each night and unless you are going to run your diesel all day, a smaller alternator won't have enough fart to fully charge the batteries, especially if it's a good day for sailing you won't run the engine enough. The 30% rule is supposed to be a ballpark for choosing alternators.

bestfriend- If you are still at Alameda let me know and I can help you install/watch/drink your beer/learn or mess things up for you

Thanks gunny. I still live in Alameda, the boats in SF. Would love to have you aboard, i'll keep you informed. You could hang out, drink beer, and jab me with the forespar right when I get really frustrated! We were supposed to go out yesterday, but if you noticed, it was pea soup and no wind. Trying to go out again next week, maybe monday, if you are up for it, I will drop you a line or PM me with your phone number.

Hoffa...sorry but that is not right. Wet cell batteries can only take about MAXIMUM of 20% of capacity during bulk charging which means that a 60amp altenator is fine for a 300ah bank.
Even with charging system loss...fully charging is simply a matter of time. Incomplete charging can happen with ANY size charger and is definitely a problem if you don't monitor what is happening in your charging routine.
He does not need a bigger or better alternator cause the boat will be MOST of the time at the dock and the charger will put on a proper charge and EQ when needed. Nothing bad is going to happen to his batteries in a week of cruising with a standard regulator even if he doesn't pull into a dock. Why spend an extra grand on a big alternator/regulator and install if you don't need it?

AGM batteries can take unlimited current and a 100amp range alternator would be more appropriate for those if a quick charge was needed. (Note: Going too much over 100amps on most sailboat engines causes bearing wear and creates a whole 'nother set of problems to deal with to insure that wear does not occur...otherwise you could add a 300 amp alternator for AGM's if you weren't worried about the horsepower loss!)

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